Power fluctuation and power loss of wind turbines due to wind shear and tower shadow

doi:10.1007/s11465-017-0434-1

Front. Mech. Eng.

2017, Vol. 12

Issue (3) : 321-332 https://doi.org/10.1007/s11465-017-0434-1

RESEARCH ARTICLE

Power fluctuation and power loss of wind turbines due to wind shear and tower shadow

Binrong WEN¹, Sha WEI¹, Kexiang WEI², Wenxian YANG³, Zhike PENG¹(

), Fulei CHU⁴

¹. Institute of Vibration, Shock and Noise, Shanghai Jiao Tong University, Shanghai 200240, China
². Hunan Province Cooperative Innovation Center for Wind Power Equipment and Energy Conversion, Xiangtan 411100, China
³. School of Marine Science and Technology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
⁴. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

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Abstract

The magnitude and stability of power output are two key indices of wind turbines. This study investigates the effects of wind shear and tower shadow on power output in terms of power fluctuation and power loss to estimate the capacity and quality of the power generated by a wind turbine. First, wind speed models, particularly the wind shear model and the tower shadow model, are described in detail. The widely accepted tower shadow model is modified in view of the cone-shaped towers of modern large-scale wind turbines. Power fluctuation and power loss due to wind shear and tower shadow are analyzed by performing theoretical calculations and case analysis within the framework of a modified version of blade element momentum theory. Results indicate that power fluctuation is mainly caused by tower shadow, whereas power loss is primarily induced by wind shear. Under steady wind conditions, power loss can be divided into wind farm loss and rotor loss. Wind farm loss is constant at 3α(3α−1)R²/(8H²). By contrast, rotor loss is strongly influenced by the wind turbine control strategies and wind speed. That is, when the wind speed is measured in a region where a variable-speed controller works, the rotor loss stabilizes around zero, but when the wind speed is measured in a region where the blade pitch controller works, the rotor loss increases as the wind speed intensifies. The results of this study can serve as a reference for accurate power estimation and strategy development to mitigate the fluctuations in aerodynamic loads and power output due to wind shear and tower shadow.

Keywords wind turbine wind shear tower shadow power fluctuation power loss

Corresponding Author(s): Zhike PENG

Just Accepted Date: 07 April 2017 Online First Date: 04 May 2017 Issue Date: 04 August 2017

Cite this article:

Binrong WEN,Sha WEI,Kexiang WEI, et al. Power fluctuation and power loss of wind turbines due to wind shear and tower shadow[J]. Front. Mech. Eng., 2017, 12(3): 321-332.

URL:

https://academic.hep.com.cn/fme/EN/10.1007/s11465-017-0434-1
https://academic.hep.com.cn/fme/EN/Y2017/V12/I3/321

Tab.1 Gross properties of the NREL 5 MW reference wind turbine [21]

Fig.1 Control strategies of the NREL 5 MW reference wind turbine [21]

Fig.2 Blade geometry of the NREL 5 MW reference wind turbine [21]

Fig.3 Velocities and forces on the airfoil

Fig.4 Calculation flowchart for the induction factors

Fig.5 Schematic diagram of the wind turbine system

Fig.6 Wind shear coefficients at different azimuths (uniform: Uniform wind speed V_H)

Fig.7 Variation in ts with the azimuth for different tower radii, d

Fig.8 Variation in ts with the azimuth for different r

Fig.9 Relationships between different steady wind speed models

Fig.10 Normalized power output of a single blade, V_H = 9 m/s (WS: Wind shear; TS: Tower shadow)

Fig.11 Variation in P with the azimuth, V_H = 9 m/s

Fig.12 Power output of the rotor versus V_H

Fig.13 Variation in power loss with hub height wind speed (the horizontal solid line represents the constant wind farm loss)

Fig.14 Power coefficient (C) versus tip speed ratio (l) performance curve

α	Wind shear exponent
R, R_hub	Rotor radius, hub radius
H	Hub height
T, Q	Axial (thrust), tangential force
C_T	Thrust coefficient
r	Air density
W	Relative velocity between blade element and inflow
V_ws, V_ts	Velocity in the wind shear and tower shadow model, respectively
C_l, C_d	Lift coefficient, drag coefficient
j	Inflow angle
V_H	Uniform wind speed
c	Chord
r	Radial distance to the rotor axis
q	Blade azimuth
B	Blade number
a, b	Axial induction factor, tangential induction factor
F_tip, F_hub	Prandtl tip factor, hub loss factor
s	Solidity, s=Bc/2pr
P1	Power output of a single blade
P	Power output of the rotor
w	Rotational speed
V₀	Local velocity of free stream
g	Twist angle
ws, ts	Wind shear and tower shadow coefficient
$V ‾ w s$ , $V ‾ t s$	Spatial average wind speed in wind shear and tower shadow model, respectively
d	Tower radius
d_t, d_b	Tower radius at the top and the bottom, respectively
x	Lateral distance from blade to tower midline; Overhang
h	Power loss
P_w	Wind farm power
C	Power capture coefficient
l	Tip speed ratio, $λ = ω R / V H$
b	Blade pitch angle
m	m=r/R

1	Thiringer T. Power quality measurements performed on a low-voltage grid equipped with two wind turbines. IEEE Transactions on Energy Conversion, 1996, 11(3): 601–606 https://doi.org/10.1109/60.537031
2	Thiringer T, Dahlberg J A. Periodic pulsations from a three-bladed wind turbine. IEEE Transactions on Energy Conversion, 2001, 16(2): 128–133 https://doi.org/10.1109/60.921463
3	Sørensen P, Hansen A D, Rosas P A C. Wind models for simulation of power fluctuations from wind farms. Journal of Wind Engineering and Industrial Aerodynamics, 2002, 90(12–15): 1381–1402 https://doi.org/10.1016/S0167-6105(02)00260-X
4	Dolan D S L, Lehn P W. Simulation model of wind turbine 3p torque oscillations due to wind shear and tower shadow. IEEE Transactions on Energy Conversion, 2006, 21(3): 717–724 https://doi.org/10.1109/TEC.2006.874211
5	Kong Y, Gu J, Wang J. Load analysis and power control of large wind turbine based on wind shear and tower shadow. Journal of Southeast University, 2010, 40(1): 228–233 (in Chinese)
6	Kong Y, Wang J, Gu J, et al.. Dynamics modeling of wind speed based on wind shear and tower shadow for wind turbine. Acta Energiae Solaris Sinica, 2011, 32(8): 1237–1244 (in Chinese)
7	Das S, Karnik N, Santoso S. Time-domain modeling of tower shadow and wind shear in wind turbines. ISRN Renewable Energy, 2011, 890582 https://doi.org/10.5402/2011/890582
8	Dai J, Hu Y, Liu D, et al.Aerodynamic loads calculation and analysis for large scale wind turbine based on combining BEM modified theory with dynamic stall model. Renewable Energy, 2011, 36(3): 1095–1104 https://doi.org/10.1016/j.renene.2010.08.024
9	Han Z, Li Y, Ji J. Numerical study on 3D steady flow of a 1.3 MW wind turbine considering wind shear factor. Journal of Chinese Society of Power Engineering, 2011, 31(10): 779–783 (in Chinese)
10	Liu L, Shi K, Yang K, et al.. Effects of wind shear on the aerodynamic load of wind turbine. Journal of Engineering Thermophysics, 2010, 31(10): 1667–1670 (in Chinese)
11	Hughes F M, Anaya-Lara O, Ramtharan G, et al. Influence of tower shadow and wind turbulence on the performance of power system stabilizers for DFIG-based wind farms. IEEE Transactions on Energy Conversion, 2008, 23(2): 519–528 https://doi.org/10.1109/TEC.2008.918586
12	Zhang J, Guo L, Wu H, et al.The influence of wind shear on vibration of geometrically nonlinear wind turbine blade under fluid-structure interaction. Ocean Engineering, 2014, 84: 14–19 https://doi.org/10.1016/j.oceaneng.2014.03.017
13	Wang H, Zhang B, Qiu Q. Numerical study of the effects of wind shear coefficients on the flow characteristics of the near wake of a wind turbine blade. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 2016, 230(1): 86–98 https://doi.org/10.1177/0957650915617855
14	Sezer-Uzol N, Uzol O. Effect of steady and transient wind shear on the wake structure and performance of a horizontal axis wind turbine rotor. Wind Energy (Chichester, England), 2013, 16(1): 1–17 https://doi.org/10.1002/we.514
15	Xing Z, Chen L, Li W, et al.Pitch control method study on reducing the effects of tower shadow and wind shear. Acta Energiae Solaris Sinica, 2013, 34(6): 916–923 (in Chinese)
16	Zhou B, Gong H, Zhen Z. The analysis of the pitch control of wind turbine by the influences of wind shear and tower shadow. Renewable Energy Resources, 2012, 30(1): 27–32 (in Chinese)
17	Bossanyi E A, Hassan G, Lane S. Individual blade pitch control for load reduction. Wind Energy (Chichester, England), 2003, 6(2): 119–128 https://doi.org/10.1002/we.76
18	Namik H, Stol K. Individual blade pitch control of floating offshore wind turbines. Wind Energy (Chichester, England), 2010, 13(1): 74–85 https://doi.org/10.1002/we.332
19	Namik H, Stol K. Individual blade pitch control of a floating offshore wind turbine on a tension leg platform. In: Proceedings of the 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. Olando, 2010 https://doi.org/10.2514/6.2010-999
20	Liao M, Xu K, Wu B, et al.. Effect of wind shear on wind turbine power. Journal of Shenyang University of Technology, 2008, 30(2): 163–167 (in Chinese)
21	Jonkman J B S, Musial W, Scott G. Definition of a 5-MW Reference Wind Turbine for Offshore System Development. NREL/TP-500-38060. 2009
22	Moriarty P J, Hansen A C. AeroDyn Theory Manual.Salt Lake City: National Renewable Energy Laboratory, 2005
23	Wu Y, Wang H. Preliminary analysis on effect of wind shear on output power for large diameter wind turbine. Energy Engineering, 2011, 6: 33–35 (in Chinese)
24	Jia Y. A wind turbine simulator for wind generation research. Acta Energiae Solaris Sinica, 2004, 25(6): 735–739 (in Chinese)
25	Li W, Xu D, Zhang W, et al.. Research on wind turbine emulation based on DC motor. IEEE Conference on Industrial Electronics and Applications, 2007, 5: 2589–2593
26	Jiang H. Power limit of horizontal axis wind turbine. Journal of Mechanical Engineering, 2011, 47(10): 113–118 (in Chinese) https://doi.org/10.3901/JME.2011.10.113
27	Burton T, Sharpe D, Jenkins N, et al.. Wind Energy Handbook. 2001.New York: John Wiley & Sons, 2014, 48–49

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